I meant design aesthetics – many modern modular oscillators (MOTM, Cwejman) are built for precision. This seems like an oscillator even Peake may like.

I would prefer to see this as a stand-alone project, separate from the SEM idea. There aren't many DIY oscillator projects. I can think of MOTM, Oakley, Thomas Henry, CGS and MFOS. Many are based on the same Electronotes oscillator from my very limited understanding. Your oscillator, based on EMS, should be a totally different sound.

I must admit that I really like the sound of those oscillators.... BEEFY!

I like the idea of a "synth voice" as well though.... Maybe the ideas aren't exclusive?

An idea.... Maybe one could merge the analog guts of something like this (JH's magic! ) with software based on the MIDIBox SID project - you can use the software without the SID to drive 8 CV outs with storage per processor, and even go up to four-voice (stereo if you want it!) pseudo poly! Maybe some day this will expand to 8 mono voices, but who knows....

The software provides two decent software DADSRs (w. level controls for A and D and curve shaping), 6 complex LFOs (with phase control and clock sync), mod matrix etc., and has a separate bassline emulation mode (for those so inclined - not so much myself!). Also, there's a pretty interesting looking programmable arpeggiator in there.... Out of the box the software should work, although a little bit kludgy.... Might need a little hacking to enhance the "fit".

Basically, what you'd need in the voice module is a great pair of oscillators (like the JH-5 examples), filters (the MS-20 LP/HP combo is great, but it would also be nice to have a good beefy 4-pole for bass and leads - maybe something like the 2040 clone?), and a quality VCA....

You could pack a LOT of power, with memory and the aforementioned features (think four-voice ana-beast!) into a two-space rack, and customize a control surface for it - everything stored in memory....

Alternately, if you want to stay in the analog domain for modulation, perhaps a second modulation board with your standard two EGs and LFOs?

Just thinking aloud, and probably getting very carried away with myself....

What would be really cool would be a polysynth mother board with slots for voice cards (say 4 or , a MIDI controller, an output processor/effects board and for a control panel interface.

If something like this existed, it would free people up to make little synth boards: get 4 Soundlabs, or 8 ASM-2s or some of these MS-20 based SEMs. Or DIY chromas. Or 3396-based systems, or systems built on Polymoog polycom cards. Or a PS3300!

The whole DIY synth movement is based on having a standard, pretty much: the 1V per 8ve standard. So it would be great to split the project into two disctinct parts: a motherboard providing these standard voice card interfaces (plus MIDI in) and some little cards for bootstrapping.

For the card interface, I am thinking of something as simple as a 32 bus in parallel to each card for shared control signal inputs (from MIDI or control panel) with generic functionality, then four dedicated inputs (KCV, gate, vel on, vel off) per card and four shared outputs (L,R, Effect send1, Effect send 2) per card, which would be about a 44pin plug including power.

there seem to be a new modular "card" format emerging, see synth diy list for details. Something like that would be definately good , or IDE cable stuff. Please spare the midibox stuff for yourself, we only need CV for first .

The original JH-4 had every parameter voltage controlled.
This was mainly because I couldn't get potentiometers with a center tap like Oberheim, and no large value log pots for the envelopes either (in the pcb mount version I wanted).
So I put everything under voltage control: A VCA for PWM would be activated for a CV larger than 5V (with all potentiometers connected to a 10V reference voltage), and a VCA for FM would be activated for CVs smaller than 5V.
At 0V, maximum FM. At 5V, no modulation. At 10V, maximum PWM.

All the boards have been connected with ribbon cables via IDC connectors. If I'd wanted to connect a programmer later (which didn't came to pass), I'd just connect the voice electronic boards and the potentiometer board to the programmer via ribbon cables, instead of directly connecting them together.
That way, a programmer could have stored the parameters of each voice independently. The whole synth would still have been programmed from the pots of the individual voice modules. You would also have been able to copy the settings of one voice module to one or several of the others, in case you wanted all voices to sound the same.

That was the concept.
I never built more than a single voice module, however.
I noticed the greates fun was to have different sounds for each voice (which *only* makes sense in combination with that brilliant, brilliant voice allocation circuit Oberheim licenced from Emu, and which, alas, has been replaced by much simpler methods in the polysynths as we know them today - but I disgress.)
So, instead of building more JH-4 modules, I hooked up my rackmount Minimoog clone, and 2 voices from the JH-3 modular system, to get the 4 voices the keyboard controller could handle.
I recorded some of my first CD with this (Of Eagles and Prophets - the "Adler" track), and then there was a terrible accident which killed most of the CMOS chips in the controller.
I plan to do a *good* version of this ever since. (Yes, I replaced the CMOS chips, and I got it working again _somehow_, but it's a real mess with dangling wires and all.)
For a new version, it would be nice to have velocity and polyphonic aftertouch, but I have no final ideas yet how to realize that.

Anyway, back the the synth modules. (We could start a separate thread for the keyboard controller if you like.)

I don't think we really need programming for a synth like this.
(Do you need programming for a modular system? Not relying on pre-programmed stuff is half of the fun, isn't it?)

And yet, the situation for potentiometers isn't much different today. Of course you can get thing custom-made, of occasionally find some odd lot to build something for yourself, but I won't rely on things like that for a huge project I'm going to sell to dozens of people.

So maybe there will be more voltage control in the new voice module than I'd originally intended.

Despite the thread title, I'm not sure about MS-20 filters either: They are attractive because they only need 6 transistors and a dual opamp for HPF + LPF. But if there is a lot of extra circuitry for the voltage control of everything, a "big" filter may make sense as well. The JH-5 had a full-fledged discrete OTA filter (what later became the MOTM 440), plus a SEM filter clone, plus an Interpolating Scanner to crossfade thru 5 filter modes. It's quite impressive to control the filter mode from Envelope 1, and simultanously control the cutofff frequeny from Envelope 2, for instance.

So I am tempted to make that new voice module bigger than intended, and closer to the JH-4. (It might still use MS-20 filters, or it might not. As I see it, that's just a minor detail of the concept.)

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

It's all open still.
We're just talking concepts now - I'm not designing anything yet.
Which version would you prefer?

JH. (in the midst of making the Dim D + T layout)_________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

I don't think we really need programming for a synth like this. (Do you need programming for a modular system? Not relying on pre-programmed stuff is half of the fun, isn't it?)

*** SNIP ***

jhaible wrote:

So maybe there will be more voltage control in the new voice module than I'd originally intended.

Despite my reference to another microprocessor based project for possible control of a poly system, I agree that programmability should not be a high priority for what you would be designing, JH....

Indeed, my earlier reference was simply that those who eventually wanted to move in that direction could do so if they wished.

I think the priority is a good sounding voice module, which allows for voltage control of the key elements. That way, you can run it direct off a panel, or wire it to a microprocessor device, or some later keyboard scanner, similar to the Obie/E-mu design, for a true analog poly.

I'm not sure about all of your designs which may be "in play" in commercial products, but my ideal synth voice would include:

- 2x VCOs with Sync option and Linear Detune (the JH-5 VCO demo is incredible! Also, I have no problem with only saw & pulse options....)
- 1x 4-Pole LPF (again, the SSM clone is ideal, but I know that one is in play already - it would be nice to have something non-moog though, for variety, but lots of girth for leads, stabs and basses. Any other ideas here?)
- 1x 2-Pole SVF (whether this takes the form of the MS-20 style, or more of an SEM style, or even something completely different.... It would be nice to have the option of the other filter states, though, as well as the softer slope....)
- 1x VCA (simply a good, stable, final VCA)

Throw a couple of EGs and basic LFOs (which one could simply not populate if they are using a micro-controlled option with those modulation generators arriving via software), and you would have the blocks of anything from a spectacular panel-controlled modular to a micro-controlled poly, to whatever....

It wasn´t. It was adressed as reply to hachiman when he said to Ricko "Please spare the midibox stuff for yourself, we only need CV for first ." (Since my post would be the next follow-up, I didn´t use quoting. Sorry).
But thank you for your extensive reply, as it helps clarifying the subject.

I´ve been following this thread with much attention since I read this paragraph of yours:

jhaible wrote:

I see people ripping out SEMs from N-Voice synths and modularizing them, and I can partly understand it, too. But for me, it’s the remaining frame that’s precious – and the actual synth modules could be about anything. (Well, not exactly anything either, but you get the idea.) The module just has to be attractive for others, too, who don’t lust after that N-Voice concept.

I´m afraid I only lust after the N-Voice concept for now, really. So I consider a Keyboard/N-CV converter to be essential. Everyone interested in this project must already own a favourite MIDI keyboard controller, hence why I can´t cope with the recent MIDI bashing messages in these forums. Maybe it´s not old enough? It was a real revolution without which we would never manage to put different standard synthesizers to talk together.
How do you expect to turn 4 monosynth modules into a polysynth using only CV? Unless you already own a cannibalized Obie frame, a Roland System 100M polykeyboard or one of the Doepfers, of course, you´ve got to use MIDI for an existing commercial keyboard. A project of a self-contained polyCV-keyboard would also be desirable, but not as easy to build. One would get a cheap Casio and install a kb scanner much like you did to the Polysix. Seems like a number of forum users have large modular set-ups with several VCOs, filters and modulators, but play them monophonically. They might welcome this idea.

Only after having that priority assured we could then start the N-module project. Otherwise you´re only debating about the same old monosynth, times four.

Sorry for sounding cynical, but if you don´t provide this facility first you might end up selling only one synth PCB per customer, not the N PCBs one would expect.Last edited by Mooger5 on Fri Jun 13, 2008 8:16 pm; edited 1 time in total

I just read what I´ve posted and it looks like I´m ranting or something, but I´m not. Just trying to make myself clear. Hope you all understand.

Best regards.

... and it's almost exactly the same thoughts I had as well.

I consider the N-Voice concept something only interesting for myself, and a handfull of others at the most, and the keyboard problem is something that can only be solved individually, salvaging a keyboard action from a broken synth. I don't expect I'll be in a position to make a deal with Fatar with this, if you know what I mean.

So, in order to be able to make an N-Voice for myself, and to share the concept with an interested _few_, I have to offer a voice module that will be attactive for _many_.
As I said, most people rip out SEMs and use them standalone. I have no problem if my JH Voice Module will be used in a similar way. I'll be happy if it's attractive enough to be bought in quantities that allow me to finance the whole project. So maybe putting my JH-5 VCOs and an Interpolating-Scanner-Multimode Filter in there might be a good idea after all.

As for Midi:
I have nothing against Midi. But I don't think there is any Midi/CV interface out there that has the Oberheim voice allocation modes *and* the same direct acess for switching of modes that the N-Voice synths had.

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

Are you gonna add a cs50/cs60/cs80 like rinmod?
I mean with an envelope vca etc.

I could certainly design a module that emulates the CS-80 ringmod and envelopes; but where would you get the single most important part of such a device: the "quadrant sliders" ?!

JH._________________"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)

on the midi affair: I think everyone is on his/her own when it comes to this matter, simple thinking leads us to "see" only CV pins. Everyone is free to open new thread by the way, thats the only thing I wanted to imply. Probably the modular synth guys already built / bought theirs, so again what are we up to - this time?

additional FX: another interesting circuit is the recent "triode emulation" which runs on 15V rails and so its eminently suited to for synth circuits. http://www.aes.org/e-lib/browse.cfm?elib=12627
paper disclosed here contains schematic, I can email it as well.

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